Mary's Sinlessness and the Atonement

So the question has been posed: if Mary was sinless for her entire life, that is, entirely perfect, then wouldn't she have been able to atone for our sins by dying on the cross?  She, too, would have been the "perfect sacrifice".

A Protestant presented her argument this way:  Had Mary been sinless throughout her life, she could have bore the sin of the world and would have been the perfect sacrifice and Jesus Christ could have stayed where He was and He wouldn't have had to humble Himself into deepest humiliation and anguish to die on the cross for our sins. If Mary had been sinless she would have been the one to fulfill the Law by keeping it perfectly.

Quick response:  Jesus' death on the cross atoned for the sins of the world not because he was sinless, but because he was GOD.

Only an infinite being can offer atonement infinitely for the sins of humankind.

Mary and the "Until" Wars

Every December Catholics will hear this objection:  Catholics say Mary was Ever-Virgin.  Yet the Bible says that Joseph didn't engage in marital relations with Mary UNTIL Jesus was born.

He had no relations with her until she bore a son,* and he named him Jesus--Matthew 1:25

Catholic response:  the above verse is important because it declares that Jesus is divine--it asserts that it is the Holy Spirit, not Joseph, who is responsible for Jesus' conception.

That's the point of the verse.  It's not a statement about the marital intimacy of Joseph and Mary.

It wants to proclaim:  Jesus is God!

Not:  Joseph and Mary were abstinent until a certain point of their marriage.

We read the Scriptures through the lens of the faith which gave us these Scriptures (that is, the Catholic Church), and understand the culture, the language, the intent of the inspired author.

And in Biblical times, the word "until" did not necessarily indicate anything which occurred subsequent to the statement. It was only an assertion about what happened prior.

To wit: "Saul’s daughter Michal was childless UNTIL the day she died"--2 Samuel 6:23

Clearly, the inspired writer is not saying that Michal had a baby AFTER she died!

And:  

"For he must reign UNTIL he has put all his enemies under his feet"--1 Corinthians 15:25

Of course the Bible isn't claiming that Jesus will stop reigning AFTER he has conquered his enemies!

Thus, the teaching on Mary's Perpetual Virginity is NOT contrary to Scripture.